Ablation catheter apparatus with one or more electrodes

ABSTRACT

A radio frequency (RF) ablation catheter has a flexible distal end portion so that it can be deflected to position an antenna disposed in the distal end portion adjacent a tissue site to be treated. At least one electrical conductor is coupled to the antenna and extends through the catheter to the proximal end of the catheter to a connector at the proximal end of the catheter for connection to a power supply for the RF antenna. At least one electrode is disposed at the distal end portion of the catheter and electrically coupled to the proximal end connector for connection to a monitor. The electrode is of a flexible, electrically conductive material such as conductive polymer material. The electrode may be an electrocardiogram (ECG) electrode.

RELATED APPLICATIONS

The present application is a continuation-in-part of co-pending U.S.patent application Ser. No. 11/359,808 of concurrent ownership, filed onFeb. 22, 2006, which is a divisional of U.S. patent application Ser. No.10/306,757, filed Nov. 27, 2002, now U.S. Pat. No. 7,004,938, whichclaims the benefit of Provisional Application No. 60/334,199, filed Nov.29, 2001 and the contents of each of these documents are incorporatedherein by reference in their entirety.

BACKGROUND

1. Field of the Invention

The present invention generally relates to medical devices used forablation of biological tissues, and more particularly to an ablationcatheter apparatus incorporating one or more electrodes such aselectrocardiogram (ECG) electrodes.

2. Related Art

Ablation catheters apply energy to a biological tissue site whichrequires ablation. Such catheters may use various energy modes, such asradiofrequency, ultrasound, laser, cryogenic, and the like. Radiofrequency (“RF”) ablation catheters generally operate in the microwavefrequency range and are used to destroy or ablate biological tissues fortherapeutic purposes. In one application, microwave ablation cathetersare used to ablate cardiac tissues that cause irregular heartbeats orarrhythmia, avoiding the need for more risky and invasive open heartsurgery. In a microwave ablation procedure, the catheter-antenna ispassed through the vein for access to the atrium. Within the atrium, theantenna is positioned at the desired location where ablation isrequired. An intracardiac electrogram is used to identify conductivepathways at the cardiac tissue site that needs to be ablated.

Prior art ablation catheters have been equipped with two or moreelectrocardiogram (“ECG”) electrode rings or buttons made ofelectrically conductive material to provide the necessary output signalfor identification of the desired ablation site. Traditionally, allcatheters used for this purpose are installed with metallic electrodes,regardless of energy mode (RF, ultrasound, laser, cryogenic, or thelike). Installing metallic electrodes over a microwave antenna hasspecial challenges. Naked metallic electrodes installed wrongly canabsorb ablation energy and become hot. Hot electrodes can have adverseeffects on the heart or other biological tissues or organs, such asblood clot formation, adherence to tissue, and tissue charring. Nakedmetallic electrodes can also impede efficient delivery of energy andhinder ablation efficiency. Additionally, metallic electrodes canseparate from the catheter when it is bent, resulting in inaccurate orlost signals.

Accordingly, what is needed is an efficient system and method forproviding an ECG output signal from an ablation catheter device.

SUMMARY

The ablation catheter system of this invention comprises an elongatecatheter adapted for insertion into a body vessel of a patient, thecatheter having a distal end portion adapted for positioning adjacent abiological tissue site requiring treatment and a proximal end portionhaving a connector for connection to a control unit for controlling theablation procedure, an antenna disposed at the distal end portion of thecatheter for providing output energy for tissue ablation purposes, apair of conductors extending through the catheter from the proximal endportion and connected to the antenna for providing power to the antennafrom a power supply in the control unit, and at least one electrodeformed of a flexible conductive material disposed at the distal endportion of the antenna and connected to the connector at the proximalend portion of the catheter for providing an output signal to thecontrol unit. The flexible conductive material is at least substantiallynon-metallic.

One or more electrodes may be disposed at the distal end portion of thecatheter. In one embodiment, the electrode or electrodes are ofconductive polymer material with hydrophilic characteristics forimproved wetability. Two spaced electrode rings are mounted on orembedded in the outer surface of the cathode. Alternatively, oneelectrode ring may be provided and the other electrode may be a tip ofconductive polymer material at the distal end of the catheter. Inalternative embodiments, layers of conductive and nonconductive polymermaterial may be provided at specific positions at the distal end portionof the catheter to produce multiple working electrodes. In each case,the electrode output signal can be connected to a suitable electroderecording system inputs in the control unit or a separateelectrocardiogram unit to provide intracardiac signal mapping.

This arrangement avoids the problems of metallic electrodes and alsoprovides electrodes which are of a flexible polymer material which canbend readily with the distal end portion of the catheter as it is shapedor bent to negotiate a path through a body vessel.

Other features and advantages of the present invention will become morereadily apparent to those of ordinary skill in the art after reviewingthe following detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The details of the present invention, both as to its structure andoperation, may be gleaned in part by study of the accompanying drawings,in which like reference numerals refer to like parts, and in which:

FIGS. 1A and 1B are side elevation views of a shapeable RF ablationcatheter according to one embodiment in a straight and bentconfiguration, respectively;

FIGS. 2A and 2B are side elevation views of a shapeable RF ablationcatheter according to another embodiment with a different steeringmechanism from FIG. 1;

FIGS. 3A and 3B are cross sectional views of the distal end portion ofthe tip of the catheter of FIG. 1 or 2 in a straight configuration and abent configuration, respectively;

FIG. 4 is a cross-sectional view of the tip or distal end portion of oneembodiment of a shapeable or bendable RF ablation catheter incorporatingelectrodes;

FIG. 5 is a cross-sectional view of the tip or distal end portion of ashapeable or bendable RF ablation catheter having a modified electrodearrangement according to another embodiment;

FIG. 6 is a cross-sectional view of the tip or distal end portion of ashapeable or bendable RF ablation catheter with another electrodearrangement;

FIG. 7 is a cross-sectional view of the tip or distal end portion of ashapeable or bendable RF ablation catheter with a modified electrodearrangement according to another embodiment; and

FIG. 8 is a cross-sectional view of the tip or distal end portion of ashapeable or bendable RF ablation catheter with modified electrodesaccording to another embodiment.

DETAILED DESCRIPTION

Certain embodiments as disclosed herein provide for systems and methodsfor ablation of biological tissues in body areas such as the heart,liver, and the like using a bendable radio-frequency (RF) catheter. Thecatheter is provided with electrodes of a flexible conductive materialsuch as a conductive polymer at its distal end for providing an outputsignal such as an intracardiac electrocardiogram (“ECG”) signal to acontrol unit to allow physicians to obtain tissue proximity andelectrical conductivity information both before and after tissueablation, as well as to provide other feedback during the ablationprocedure.

After reading this description, it will become apparent to one skilledin the art how to implement the invention in various alternativeembodiments and alternative applications. However, although variousembodiments of the present invention will be described herein, it isunderstood that these embodiments are presented by way of example onlyand not limitation. As such, this detailed description of variousalternative embodiments should not be construed to limit the scope orbreadth of the present invention as set forth in the appended claims.

FIGS. 1A and 1B illustrate a radio-frequency (“RF”) ablation cathetersystem 100 of one embodiment including a shapeable catheter device 100adapted for insertion into a body vessel of a patient and incorporatingan RF antenna for delivering electromagnetic energy to a treatment site,as described in more detail below.

The catheter device 100 has a flexible, elongated tubular body 120having a proximal portion 130 and a distal or tip portion 140. Locatedat the proximal portion of the body is a handle chassis 160 containingsteering and positioning controls (not illustrated) for the body,activated by actuator 200. In the embodiment of FIGS. 1A and 1B, the tipportion of the catheter body is activated to bend between the straightconfiguration of FIG. 1A and the bent configuration of FIG. 1B bysliding the actuator back and forth in an axial direction. In themodified embodiment of FIGS. 2A and 2B, the tip portion is bent betweenthe straight and bent configurations by rotating the actuator or collar220. Suitable mechanisms for controlling bending of the tip portion ofcatheter body 120 are described in detail in U.S. Pat. No. 7,004,938 ofOrmsby et al., the contents of which are incorporated herein byreference. However, it will be understood that any suitable mechanismmay be incorporated in the catheter device in order to control thebending or steering of the tip portion as it moves through a bodyvessel, organ, or cavity.

A coupling or electrical connector 170 is provided at the proximal endof the catheter device for connecting the catheter to a control unit orthe like containing one or more electronic devices such as an RFgenerator and controller (not shown) for providing power to the antennaduring an ablation procedure. Suitable signal control units are known inthe ablation catheter field and are therefore not described in detailhere.

The dimensions of the catheter body are adapted as required to suit theparticular medical procedure, as is well known in the medical art. Inone embodiment, the catheter is used to ablate cardiac tissue. However,the catheter may be used to ablate other types of body tissue indifferent organs, both internal and external to the body. The tubularbody 120 of the catheter device may be generally constructed of apolymer material which is bio-compatible with the body vesselenvironment. Examples of such materials include thermoplastic elastomermaterial such as Pebaxg available from Autochem Germany, polyethylene,polyurethane, polyester, polyimide, polyamide, and the like, withvarying degrees of radiopacity, hardness, and elasticity.

The tubular body of the catheter may be formed with a plurality ofsegments using one or more of the aforementioned materials orequivalents, such that the catheter body 120 is progressively moreflexible towards its distal end. The segments may be joined together bythermal bonding, butt joints, or adhesive bonding. Braidingreinforcement may be provided to the surface of the tubular body toattain a desirable level of stiffness and torsional strength for thecatheter to advance and negotiate through the body vessel of thepatient, while still allowing the distal end portion to be bent whenneeded. The distal end portion 140 may be of a softer polymer compoundthan the remainder of the body, with little or no braiding orreinforcement, to provide the desired flexibility for distal deflectionand shaping of the apparatus.

The structure of the catheter in one embodiment will now be described inmore detail with reference to FIGS. 3A and 3B. As noted above, thecatheter has a tubular body with a central bore 150 and a closed distalend or tip. The tip may be open in alternative embodiments. In theillustrated embodiment, deflection of the distal end portion of thecatheter is accomplished by use of a pre-shaped deflection member 180which is constrained in a straight orientation in the configuration ofFIG. 3A and which adopts a bent shape when extended into the bentconfiguration of FIG. 3B. However, it will be understood that otherbending or shaping mechanisms may be used in alternative embodiments, asdescribed, for example, in U.S. Pat. No. 7,004,938 referenced above. Thedistal end portion 140 of the tubular body includes an RF antenna 250comprising a flexible, helically coiled radiating antenna device 255embedded in the flexible wall of the tubular body, as best illustratedin FIGS. 3A and 3B. The antenna device can therefore bend as the distalend portion is shaped to conform to a body vessel or the like, asillustrated in FIG. 3B. Opposite ends of the antenna device areconnected to electrical conductors or leads for connection to theproximal end connector 170 and thereby to a source of RF energy in thecatheter control unit (not illustrated), as will be described in moredetail below in connection with FIG. 4. Other antenna devices may beprovided in alternative embodiments, and the diameter, pitch and lengthof the coiled device 255, and the conductive material used for thedevice 255, may vary according to the particular procedure andflexibility requirements.

The electrical conductors which connect the RF antenna to the connector170 may be of a flexible mesh or braided wire construction 260 or of athin-film electrically conductive material. In the embodimentillustrated in FIGS. 3A and 3B, the conductors are shown schematicallyas a mesh construction embedded in the walls of the tubular body 120 ofthe catheter. In alternative arrangements, separate conductors may beused to provide power to the antenna 250. FIG. 4 illustrates the distalend portion 310 of a first embodiment of a modified catheter havingintegrated electrodes 312, 314. In one embodiment, the electrodes areECG electrodes, although they may be other types of electrodes in otherembodiments. Although two electrodes are illustrated in FIG. 4, in otherembodiments one electrode or more than two such electrodes may beprovided. Some parts of the catheter of FIG. 4 are identical to those inFIGS. 1 to 3 and like reference numerals have been used for like parts,as appropriate. In the embodiment of FIG. 4, a pair of coaxial inner andouter tubular conductors 315, 316 extend along the length of the tubularbody 318, with the outer conductor 316 connected to the proximal end ofRF antenna 250 and the inner conductor 315 connected to the distal endof the RF antenna adjacent the tip of the catheter. The structure of theremainder of the tubular body 318 which is not shown in FIG. 4 may beidentical to that of tubular body 120 described above, and a similarconnector 170 (not illustrated) may be provided at the proximal end ofthe catheter for connecting the conductors to a suitable RF source. Thedistal end portion illustrated in FIG. 4 will be shapeable or bendablein a similar manner and using the same or similar control devices aswere described above in connection with FIGS. 1 to 3.

In the embodiment of FIG. 4, the tubular body 318 is of dielectricmaterial such as a non-conductive polymer and has a portion 320 ofreduced outer diameter at its forward end. The first electrode 312comprises a sleeve of flexible conductive material mounted over thereduced diameter end portion 320 of the tubular body and having an endportion or tip 322 extending over the open end of portion 320. The RF ormicrowave antenna 250 is embedded in the sleeve or electrode 312. Theinner and outer conductors 315, 316 extend through the tubular body 318as illustrated for connection to the opposite ends of the antenna coil250. The second electrode 314 comprises a ring of flexible conductivematerial mounted over the tubular body 318 at a location spacedrearwardly from the rear end of conductive sleeve or electrode 312. Thetwo electrodes may be secured over the inner tubular body 318 byadhesive, bonding, mechanical force, heat sealing or the like. Theflexible conductive material forming the electrodes is at leastsubstantially non-metallic material and may be a conductive polymermaterial which is sufficiently bendable to allow bending of the distalend portion 310 between the positions illustrated in FIGS. 1A and 1B.

In an alternative embodiment, the electrode ring 314 may be mountedflush in an annular recess or gap in the outer surface of the tubularbody, or may be molded integrally with the tubular body, so that it doesnot project outwardly from the outer surface of the body 318. Aconductor or connector 324 extends from electrode ring 314 to theconnector 170 at the proximal end of the catheter, for suitableconnection to an ECG monitor or the like in a control unit (notillustrated) for the catheter. Conductor 324 is shown spaced from theouter surface of body 318 in FIG. 4 for clarity, but may be a line ofconductive ink or adhesive over the outer surface of the tubular body,or may alternatively be embedded in the body 318 outside conductor 316,One of the conductors 315 or 316 will also be connected to the ECG orother monitor for suitable monitoring of the signal detected between thetwo electrodes 312, 314. In one embodiment, both electrodes are of aflexible, conductive polymer material, i.e. a polymer material loadedwith conductive materials.

FIG. 5 illustrates the distal end portion 325 of a catheter with amodified electrode arrangement in which the electrode ring 314 of FIG. 4is replaced by an electrode end cap 330. Electrodes 312, 330 are offlexible conductive material such as a conductive polymer material as inFIG. 4. In this embodiment, the conductive sleeve 312 in which theantenna is mounted has an outer cover layer 332 of non-conductivepolymer material extending along at least part of its length and overits distal end, providing a non-conductive shield layer between thefirst and second electrodes 312, 330. A conductor or connector wire 334extends from the connector at the proximal end of the catheter throughthe central lumen 150 of the tubular body 318 and into the electrode endcap 330 to provide a signal path between the electrode and the ECGmonitor. The catheter of FIG. 5 is otherwise identical to that of theprevious embodiment and like reference numerals have been used asappropriate. Conductive sleeve 312, non-conductive layer 332, and endcap 330 may be laminated together over the tubular body 318 by anysuitable means such as bonding, heat sealing, adhesive, or the like.

FIG. 6 illustrates the distal end portion 340 of a catheter havinganother modified electrode arrangement. Parts of the cathode of thisembodiment are identical to those of FIGS. 4 and 5 and like referencenumerals have been used for like parts as appropriate. Unlike theprevious embodiments, the sleeve 335 in which the antenna coil 250 isembedded does not comprise one of the two electrodes. As in the previousembodiment, sleeve 335 is mounted over the reduced diameter end portion320 of the tubular body 318, which is of dielectric or non-conductivematerial, and the antenna coil 250 is connected at its opposite ends tothe distal ends of the inner and outer conductors 315, 316.

In the embodiment of FIG. 6, an outer layer 336 of non-conductivematerial, such as a non-conductive polymer material, extends over theconductive sleeve 335 and has an end cap portion 338 extending over thetip of the tubular body 318. The electrodes in this embodiment comprisea pair of conductive rings 339, 341 mounted at spaced intervals on theouter, non-conductive layer 336. The ring electrodes may be ofconductive polymer material. The first ring 339 is positioned adjacentthe non-conductive end cap portion 338 and the second ring 341 ispositioned adjacent the rear end of the conductive layer 336. A centralconductor or connector wire 342 extends through the hollow central boreor lumen of the tubular body 318, through the non-conductive end capportion 338, and bends back to terminate in the first conductive ringelectrode 339. In one embodiment, the part of connector wire 342 shownextending through lumen 150 may be a line of conductive ink or adhesiveon the inner surface of tubular body 318. A second conductor orconnector wire 343 extends along the outside of the tubular body 318 andis connected to the second conductive ring electrode 341. It will beunderstood that the connector wire 343 may comprise a line of conductiveink or adhesive on tubular body 318, or may alternatively be embedded inthe tubular body 318 at location spaced outside the outer tubularconductor 316. The various conductive and non-conductive polymer layersof the distal end portion 340, including the electrode rings, aresuitably laminated together by heat sealing, adhesive bonding, or thelike.

Also shown in FIG. 6 is a pull wire 355 which extends through the lumen150 to the tip 338 and is attached to suitable steering and positioningcontrols (not illustrated) at the proximal end of the catheter, forcontrolling bending of the distal end portion. Such a pull wiremechanism is described in U.S. Pat. No. 7,004,938 referenced above, thecontents of which are incorporated herein by reference. It may beunderstood that a similar position control mechanism will be provided inthe embodiments of FIGS. 4 to 6, or the mechanism 180 of FIG. 3 may beprovided in any of these embodiments.

FIG. 7 illustrates the distal end portion 400 of a catheter according toanother embodiment. Again, some parts of the catheter illustrated inFIG. 7 are identical to those of FIGS. 4 to 6 and like referencenumerals have been used as appropriate. As in the previous embodiment, atubular body 318 of flexible dielectric material extends the length ofthe catheter and has a central through bore or lumen 150 and an endportion 320 of reduced outer diameter over which the sleeve 312containing embedded RF antenna 250 is mounted. As in the previousembodiments, sleeve 312 is of conductive polymer material and the endsof the antenna are connected to the distal end connector 170 (FIG. 1) ofthe catheter by means of inner and outer cylindrical conductors 315, 316extending through the tubular body 318, in the manner described above inconnection with FIG. 1. Unlike the previous embodiments, an outer coverlayer 345 of non-conductive polymer material extends along the entirelength of the catheter, over the tubular body 318 and sleeve 312, andhas a forward end or tip 344 covering the forward end of the sleeve andtubular body. A pair of contact rings 346,348 are mounted in the outercover layer 345 in the distal end portion of the catheter, with theforward contact ring 346 located over the sleeve 312 and in electricalcontact with the sleeve, and the rear contact ring 348 located slightlyrearwardly from sleeve 312. Each ring is of a flexible conductivematerial such as conductive polymer material. Rings 346,348 and outercover layer 345 are suitably bonded together and laminated over thetubular body 318 and conductive polymer sleeve 312.

The forward contact ring 346 is connected to the proximal end connector170 via the conductive sleeve 312 and the outer conductor 316 which alsoprovides power to the antenna 250. The rear contact ring 348 isconnected to a conductive wire 350 which extends through the tubularbody 318 to the proximal end connector 170 of the catheter. Theconductors 316, 350 therefore provide the output for the ECG monitor inthe control unit in this embodiment.

The embodiment of FIG. 7 also includes a temperature sensor 352 in thelumen 150 adjacent the tip of the catheter. In the illustratedembodiment, the temperature sensor 352 may be a thermistor,thermocouple, or the like and has a thermocouple junction or sensor end352 and a pair of braided wires or conductors 354 extending from thesensor 352 through the tubular body to the connector 170 at the proximalend of the catheter, where they are connected to control circuitry formonitoring the temperature at the distal end of the catheter andcontrolling the antenna operation. A pull wire 355 is attached to thetip 344 of the catheter and extends through the central lumen 150through the length of the catheter for attachment to a suitable steeringand control mechanism (not illustrated), as in the previous embodiment.

A system for monitoring and controlling operation of an RF ablationcatheter incorporating a temperature sensor is described in co-pendingapplication Ser. No. 11/479,259 filed on Jun. 30, 2006, the contents ofwhich are incorporated herein by reference. It will be understood that asimilar control system may be provided for controlling operation of themicrowave antenna in this embodiment or other embodiments describedabove, with suitable inclusion of a temperature sensor.

FIG. 8 illustrates a modification of the embodiment of FIG. 5, and likereference numerals are used for like parts as appropriate. In thisembodiment, as in the previous embodiments, a tubular body 318 ofdielectric material having a central lumen 150 extends the entire lengthof the catheter, and has a reduced outer diameter portion 320 at thedistal end portion 500 of the catheter. Conductive sleeve 312 is mountedover the portion 320 and the RF antenna 250 is embedded in sleeve 312.As in the embodiment of FIG. 5, the electrodes comprise the conductivesleeve 312 and a conductive tip 330 mounted over the end of thecatheter, with a layer 332 of non-conductive material such asnon-conductive polymer between the electrodes 312 and 330. The variouslayers of conductive and non-conductive materials in the embodiment ofFIG. 8 will also be laminated together by any suitable means such asheat, adhesives and mechanical force.

In FIG. 8, the conductive wire 334 which is connected to the conductivetip electrode 330 of FIG. 5 is eliminated, and is replaced with doublethermocouple wires 510 which extend through lumen 150 from the proximalend connector 170 of the catheter and into the conductive tip electrode330, with a thermocouple junction 512 at the end of the double wiresproviding a temperature sensor. The thermocouple wires therefore havethe dual function of providing a temperature sensor output as well asproviding an ECG monitor output in combination with outer antennaconductor 316. The ECG output may be measured between conductor 316 andeither one of the thermocouple wires 510. The temperature output may beused in monitoring and controlling operation of the RF antenna, asdescribed above in connection with FIG. 7.

In each of the embodiments of FIGS. 4 to 8, electrodes are mounted atthe distal end portion of a shapeable or bendable catheter to allowphysicians to locate a tissue region causing problems and to obtain bothoptimum tissue proximity and electrical conductive activities before andafter ablation, as well as to obtain feedback of their actions. Althoughtwo electrodes are provided in these embodiments, only one electrode ormore than two electrodes may be provided in other embodiments. Theelectrode or electrodes in these embodiments may be ECG or other typesof electrodes. Radio-opaque markers (not illustrated) at the distal endportion of the catheter may also be used to aid in positioning the tipof the catheter, as is known in the field. Where the electrodes are ECGelectrodes, it will be understood that the conductor wires connected tothe electrodes and to the proximal end connector 170 of the catheterwill communicate with an external ECG system and monitor (notillustrated) via a suitable connection cable which will transmit ECGsignals between the electrodes and ECG system. The antenna conductorsand thermocouple wires (if a temperature sensor is present) will besimilarly connected to an appropriate antenna output control system.

In each of the above embodiments, the RF antenna 250 is adapted toreceive and radiate electromagnetic energy in order to treat a selectedbiological tissue site. An example of a suitable spectrum of radiofrequency energy for use in the ablation catheter is that of themicrowave frequency range above 300 MHz. The RF antenna is capable ofapplying substantially uniformly distributed electromagnetic fieldenergy along the RF antenna in a direction substantially normal to thelongitudinal axis of antenna 250.

The electrodes in the embodiments of FIGS. 4 to 8 are made of a suitableflexible conductive material, so that they can bend with the remainderof the distal end portion during steering. Such electrodes avoid orreduce the problems encountered with metallic electrodes, since they donot absorb microwave energy to any great extent and do not becomeexcessively hot. The electrodes may be of an at least substantiallynon-metallic material, and in one embodiment they are made from aconductive polymer material such as nylon, polyethylene, polyolefin,polypropylene, polycarbonate, Pebax®, TPE (thermoplastic elastomers) andblends, loaded with a selective conductive material. Othernon-conductive parts of the catheter may be of the same polymer materialor different polymer materials. The conductive material may bemicro-carbon spheres, carbon particles, carbon nanotubes, nickel dust,or the like. The electrodes may be made entirely of conductive polymermaterial or may be a mixture of conductive and non-conductive polymermaterial, or a mixture of conductive and non-conductive materials withmetal substrates. The composite polymer material is selected to have arelatively low resistance for reduced interference with the microwaveradiation pattern, and to be hydrophilic for improved wetability on theouter surface of the catheter.

Communication between the electrodes and the connector 170 at theproximal end of the catheter may be provided in some embodiments bymeans of conductive ink or adhesive applied over the polymer surface.For example, conductor 324 of FIG. 4 or conductor 342 of FIG. 6 may be aline of conductive ink or adhesive over the outer surface of the tubularbody 318 extending from electrode ring 314 to the proximal end of thecatheter. Conductor 350 of FIG. 7 may be a line of conductive ink oradhesive over the outer surface of non-conductive tubular body 318, withthe outer layer 345 of non-conductive polymer laminated over the tubularbody and conductor line 350.

Heat energy, adhesives, and/or mechanical force may be used to laminatethe conductive and non-conductive polymer layers in the embodiments ofFIGS. 4 to 8. Metallic substrates may also be laminated between thepolymer layers, such as the inner and outer tubular conductors whichprovide power for operating RF antenna 250.

The above description of the disclosed embodiments is provided to enableany person skilled in the art to make or use the invention. Variousmodifications to these embodiments will be readily apparent to thoseskilled in the art, and the generic principles described herein can beapplied to other embodiments without departing from the spirit or scopeof the invention. Thus, it is to be understood that the description anddrawings presented herein represent a presently preferred embodiment ofthe invention and are, therefore, representative of the subject matterwhich is broadly contemplated by the present invention. It is furtherunderstood that the scope of the present invention fully encompassesother embodiments that may become obvious to those skilled in the artand that the scope of the present invention is accordingly limited bynothing other than the appended claims.

1. An RF ablation catheter apparatus, comprising: an elongate catheteradapted for insertion into a body vessel of a patient, the catheterhaving a proximal end and a distal end portion, at least the distal endportion of the catheter being flexible for allowing the distal endportion of the catheter to be deflected; a radio-frequency (“RF”)antenna disposed at the distal end portion of the catheter and adaptedto receive input RF energy for the ablation of biological tissue; anelectrical connector at the proximal end of the catheter for connectionto a power supply for the RF antenna; and at least one electrodedisposed at the distal end portion of the catheter and electricallycoupled to the connector at the proximal end of the catheter forconnection to a monitor; the electrode being of a flexible, electricallyconductive material.
 2. The apparatus of claim 1, wherein the electrodeis an electrocardiogram (“ECG”) electrode.
 3. The apparatus of claim 1,wherein the electrode material is an at least substantially non-metallicmaterial.
 4. The apparatus of claim 3, wherein the electrode material isa flexible conductive polymer material.
 5. The apparatus of claim 1,wherein the electrically conductive material comprises a flexiblepolymer material loaded with a conductive material.
 6. The apparatus ofclaim 5, wherein the polymer is selected from the group consisting ofpolyethylene, polyolefin, polypropylene, polycarbonate, nylon andthermoplastic elastomer material.
 7. The apparatus of claim 5, whereinthe conductive material is selected from the group consisting ofmicro-carbon spheres, carbon particles, carbon nanotubes, and nickeldust.
 8. The apparatus of claim 1, further comprising at least oneelectrical conductor extending through the catheter and coupled at afirst end to the antenna and to the proximal end connector at a secondend.
 9. The apparatus of claim 1, wherein the catheter comprises atubular body and the electrode comprises a ring mounted on said tubularbody.
 10. The apparatus of claim 1, wherein at least two spacedelectrodes are disposed at the distal end portion of the catheter. 11.The apparatus of claim 10, wherein at least a portion of the tubularbody at the distal end of the catheter is of non-conductive material andsaid electrodes comprise spaced rings on the non-conductive portion ofsaid tubular body.
 12. The apparatus of claim 1, wherein the electrodecomprises an elongate sleeve at the distal end portion of said catheter.13. The apparatus of claim 11, wherein the antenna comprises a helicalcoil embedded in said electrode sleeve, and at least one electricalconductor for connecting the antenna to an RF power source to provide anelectrical connection from said electrode sleeve to said proximal endconnector.
 14. The apparatus as claimed in claim 13, wherein theelectrical conductor is coupled to a first end of the helical coil and asecond electrical conductor is coupled to a second end of the helicalcoil and extends through the catheter to the proximal end connector. 15.The apparatus as claimed in claim 11, further comprising a secondelectrode of flexible, electrically conductive material spaced from saidconductive electrode sleeve.
 16. The apparatus as claimed in claim 11,further comprising an outer layer of non-conductive material extendingover at least part of the electrode sleeve, and a second electrode offlexible, electrically conductive material mounted on said outer layer.17. The apparatus as claimed in claim 16, wherein the second electrodecomprises an end cap extending over the distal end of the catheter andat least part of the said outer layer.
 18. The apparatus as claimed inclaim 17, further comprising an electrical conductor extending throughsaid catheter and coupled to said end cap for electrically connectingthe end cap to the proximal end connector of the catheter.
 19. Theapparatus as claimed in claim 1, further comprising a temperature sensormounted in the distal end portion of the catheter and a pair ofthermocouple wires connected to said temperature sensor and extendingthrough the catheter to said proximal end connector.
 20. The apparatusas claimed in claim 19, wherein said temperature sensor is coupled tothe electrode and one of said thermocouple wires further comprises theelectrical coupling from the second electrode to the proximal endconnector.
 21. The apparatus as claimed in claim 20, wherein theelectrode comprises an end cap at the distal end of the catheter, andthe temperature sensor is embedded in the end cap.
 22. The apparatus asclaimed in claim 1, wherein the catheter comprises a tubular bodyextending from the proximal end to the distal end of the catheter, thetubular body being of non-conductive material, and an outer sleeve ofconductive material mounted over the distal end portion of the tubularbody and containing the RF antenna, the electrode comprising a ringelectrically isolated from the outer sleeve.
 23. The apparatus asclaimed in claim 22, wherein the electrode ring is mounted over thetubular body at a location spaced from the outer sleeve.
 24. Theapparatus as claimed in claim 23, wherein the outer sleeve comprises asecond electrode electrically coupled to the proximal end connector. 25.The apparatus as claimed in claim 23, further comprising a layer ofnon-conductive material extending along at least part of the length ofthe outer sleeve, and a second electrode mounted on said layer ofnon-conductive material.
 26. The apparatus as claimed in claim 1,further comprising a deflection member adapted to control deflection ofthe distal end portion of the catheter.
 27. An RF ablation catheterapparatus, comprising: an elongate catheter adapted for insertion into abody vessel of a patient, the catheter having a proximal end and adistal end portion, at least the distal end portion of the catheterbeing flexible for allowing the distal end portion of the catheter to bedeflected; a radio-frequency antenna disposed at the distal end portionof the catheter and adapted to receive input RF energy for ablation ofbiological tissue; an electrical connector at the proximal end of thecatheter for connection to a power supply for the RF antenna; a pair ofinner and outer coaxial electrical conductors extending through thecathode from said antenna to said electrical connector; and at least oneelectrode disposed at the distal end portion of the catheter andelectrically coupled to the connector at the proximal end of thecatheter for connection to a monitor, the electrode being of a flexible,electrically conductive material.
 28. The apparatus of claim 27, whereinthe antenna comprises a helical coil embedded in the distal end portionof the catheter, the coil having first and second ends, and the coaxialelectrical conductors being coupled to the first and second ends of thecoil, respectively.
 29. The apparatus of claim 27, wherein the electrodecomprises an elongate sleeve at the distal end portion of the catheter.30. The apparatus of claim 29, further comprising a second electrode offlexible, electrically conductive material spaced from the conductiveelectrode sleeve.
 31. The apparatus of claim 29, wherein the antenna isembedded in said electrode sleeve.
 32. The apparatus of claim 27,wherein at least two spaced electrodes of flexible, electricallyconductive material are disposed at the distal end portion of thecatheter and coupled to the electrical connector for connection to amonitor.
 33. The apparatus of claim 32, wherein the electrode materialis a flexible conductive polymer material.
 34. The apparatus of claim32, wherein the electrodes comprise spaced electrode rings.